Method and apparatus for quench hardening elongated workpieces

ABSTRACT

A method and apparatus for quench hardening a plurality of successive elongated workpieces supported on a carrier and movable in a generally circular path from a loading station, to a heating station, and then through a quench hardening station wherein the members supporting the workpieces on the carrier are independently movable with respect to the other members of the carrier, at least in the vicinity of the quenching station.

United States Patent Sheetz [451 Dec. 12,1972

[54] METHOD AND APPARATUS FOR QUENCH HARDENING ELONGATED WORKPIECES [72] Inventor: Richard S. Sheetz, Shaker Heights,

Ohio

[73] Assignee: Park-Ohio Industries, Inc., Cleveland, Ohio [22] Filed: Oct. 1, 1970 211 Appl. No.: 77,278

[52] US. Cl. ..266/4 A, 148/143, 266/4 E [51] Int. Cl. ..C2ld 1/66 [58] Field of Search ..148/12.4, 143, 144, 153; 266/4 R, 4 A, 4 E; 219/10.69, 159

[56] References Cited UNITED STATES PATENTS 3,293,086 12/1966 Seulen et al. ..266/4 A 3,383,100 5/1968 Balger et al ..266/4 A Primary Examiner-Gerald A. Dost Attorney-Meyer, Tilberry and Body [57] ABSTRACT A method and apparatus for quench hardening a plurality of successive elongated workpieces supported on a carrier and movable in a generally circular path from a loading station, to a heating station, and then through a quench hardening station wherein the members supporting the workpieces on the carrier are independently movable with respect to the other members of the carrier, at least in the vicinity of the quenching station.

5 Claims, 3 Drawing Figures PATENTEDnEc I 2 I972 3. 705, 7 15 IN VENTOR.

RICHARD S. SHEETZ BY M 744%, g M,

ATTORNEYS METHOD AND APPARATUS FOR QUENCH HARDENING ELONGATED WORKPIECES This invention relates to the art of induction heating and quench hardening a workpiece, and more particularly to a method and apparatus of quench hardening a succession of workpieces in a continuous fashion.

The invention is particularly applicable for quench hardening the body of an axle shaft, and it will be 7 described with particular reference thereto; however, it should be appreciated that the invention has much broader applications and may be used for quench hardening various other elongated workpieces, such as the bearing surfaces of a crankshaft.

For several years, it has been suggested to harden the body of an axle shaft by rotating the axle shaft adjacent an induction heating inductor. Thereafter, the heated axle shaft was quench hardened by spraying a quenching fluid onto the heated body or by moving the axle shaft into a quench tank. The present invention relates to a system of the type using a quench tank into which the axle shaft is moved after the body has been inductively heated. At first, this type of system, using a quench tank, involved a heating station above the tank. The axle shaft was rotated adjacent appropriate inductors to heat the bearing surfaces. Thereafter, the axle shaft was moved downwardly into the quench tank. This operation was somewhat time consuming, and efforts were made to increase the productivity of such a system for heating and quench hardening an axle shaft by using a quench tank. It was suggested to use a carrier having a plurality of work piece holding members extending outwardly from a common axis. An axle shaft was placed onto each of these members, and the shafts were successively heated and quenched by indexing the heated axle shafts into a quench tank. After the shafts were quench hardened, the carrier was unloaded and a new group of shafts were loaded onto the carrier. This operation again consumed a substantial amount of time. To overcome this, the use of two oscillating workpiece carriers was suggested. One carrier was loaded with a shaft and the shaft was heated while the other carrier was within the quench tank hardening a previously heated shaft. Thereafter, the heated axle shaft was moved into the quench tank while the hardened axle shaft was withdrawn from the tank and unloaded from the carrier. Thereafter, this cycle was repeated. Again, this did not provide a completely continuous operation.

It was then suggested to provide a carrier having at least three workpiece receiving members and movable about a common axis so that the members were successively indexed between a loading station, a heating station and a quenching station within a quench tank. At the loading station, the hardened workpiece was removed and an unhardened workpiece was inserted. At this same time, a workpiece at the heating station was being inductively heated. After an unheated workpiece was placed onto the member at the loading station, the carrier was indexed. This plunged the inductively heated workpiece into the quench tank and moved the unhardened workpiece to the heating station. By repeating this process, successive workpieces were hardened. This type of apparatus did provide substantially continuous operation; however, it exhibited one distinct disadvantage. Unloading and loading an axle shaft onto the carrier at the loading station often required more time that the heating cycle. This was especially true when the loading and unloading was manually performed. Consequently, this type of apparatus required an auxiliary spray quench so that the quenching operation could commence immediately after the heating cycle, irrespective of whether an operator had removed the workpiece and replaced it with an unheated workpiece at the loading station. It was impractical to plunge the heated workpiece into the quench tank immediately after the heating cycle terminated due to the delay at the loading station. If the quench spray arrangement was not included, the hardness of the previously heated bearing surfaces would not be satisfactory. The temperature would be reduced or the heating pattern would be conducted inwardly to a depth unsatisfactory for a hardened bearing surface. As another approach the heating cycle was started later or after the loading was completed. This required more controls and increased the indexing time.

All of these disadvantages of prior arrangements for quench hardening an elongated workpiece, such as an axle shaft, have been overcome by the present invention which utilizes the continuous carrier concept, but provides for immediate quenching after the heating cycle irrespective of other unfinished tasks.

In accordance with the present invention, there is provided a carrier for moving an elongated workpiece in a generally circular path from a loading station, to an induction heating station and then through a quenching station. This carrier has at least three members for supporting the workpieces and means for allowing independent movement of each of the members with respect to the other members of the carrier, at least from the heating station to the quenching station. By constructing a carrier in this manner, the workpiece may be immediately quenched without affecting the indexing operation of the carrier itself.

In accordance with another aspect of the present invention, there is provided a method of inductively heating and quench hardening an elongated workpiece which method includes the steps of providing a carrier having at least three workpiece receiving members; moving the members, in a path defining a circle about an axis, from a loading station, to a heating station and then through a quenching station; loading a workpiece into one of the members at the loading station; indexing the carrier to move the workpiece into the heating station; inductively heating the workpiece at the heating station; and, moving the workpiece through the quenching station independently of the other members on the carrier.

The primary object of the present invention is the provision of a method and apparatus for quench hardening an elongated workpiece, which method and apparatus includes the use of a carrier for moving a workpiece from a loading station, to a heating station and then through a quenching station, wherein a workpiece can be moved independently of the carrier from the heating station to the quenching station without being removed from the carrier.

Another object of the present invention is the provision of a method and apparatus for quench hardening an elongated workpiece which method and apparatus includes the use of a carrier for moving a workpiece from a loading station, to a heating station and through lOl0 0290 a quenching station, wherein the workpiece can be moved independently of the carrier in the quenching station to provide uniform quenching.

These and other objects and advantages will become apparent from the following description taken with the accompanying drawings in which:

FIG. 1 is a schematic view illustrating the present invention;

FIG. 2 is a schematic, enlarged cross-sectional view showing one feature of the preferred embodiment of the present invention; and,

FIG. 3 is an enlarged partial, schematic view taken generally along line 3-3 of FIG. 2.

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting same, the figures show an apparatus A for inductively heating and then quench hardening a workpiece B, in the form of an axle shaft, in a quench tank C filled by a quenching fluid to a level 10. As shown in FIG. 1, apparatus A includes a loading station I, a heating station II, and a quenching station III. A schematically illustrated carrier 20 includes three radially extending support arms 22, 24, 26. The carrier is indexed by a means, not shown, about an axis a. In accordance with the present invention, which will be described later in more detail, each of the arms 22, 24, 26 can be indexed into the positions shown in solid lines or independently moved with respect to the carrier.

In operation, the workpiece B is loaded onto one of the arms at station I. The carrier is then indexed to bring this workpiece to position II. At that position, well known induction heating inductor D is used for inductively heating the body of axle shaft B. Immediately after the heating cycle has been completed, the arms carrying the heated workpiece are moved downwardly into the quench tank C, independently of movement of the carrier itself. This is shown in phantom position at the left. Consequently, the quenching can take place immediately after the heating without waiting for loading of a subsequent workpiece onto the carrier at position I. After the workpiece is moved into the quench tank, it is then moved further to the solid line position of arm 26. This requires the upward swinging movement of the workpiece which had been assuming this position. As soon as the workpiece has been loaded at position I, the carrier 20 is indexed which raises one of the arms into position I, moves the other arm into position II, and retains the previously heated workpiece in the solid line position within tank C. This operation is continued. Two advantages are realized. First, without indexing the carrier 20 the heated workpiece can be immediately moved into the tank C. In addition, the speed of movement of the heated workpiece to the solid line position within the tank can be more gradual than that determined by the indexing speed of the carrier 20. It is appreciated that more than three support arms could be provided for the carrier 20 without departing from the intended spirit and scope of the invention. In addition, it should be realized that each support arm 22, 24, 26 is arranged in pairs with the second support arm on the opposite end of the workpiece, and not shown in the figures.

A variety of structures could be used for providing independent movement of the support arms with respect to the carrier to accomplish the purposes described above. In accordance with the illustrated embodiment of the invention, as shown in FIGS. 2 and 3, the apparatus A includes an internal support shaft 30 which is stationary. Rotatable sleeves 32, 34, 36 are journalled to rotate as a unit, or independently about the support shaft 30. Each of the sleeves has relatively small mounting elements 40, 42, 44 for arms 22, 24, 26, respectively. The remainder of the circumference of the sleeves adjacent the mounting elements is removed to allow relative movement of the respective support arms. As shown in FIG. 3, the workpiece B is supported between two axially spaced support arms, only one of which is shown, as support arm 22. When an axle shaft is being quench hardened, the workpiece B includes body 50, and is supported to be rotated about axis b by support head 52. This head includes appropriate means for rotating the workpiece at the heating station while inductor D is positioned adjacent the body 50. A wide variety of control structures could be used for effecting the movement discussed with respect to FIG. 1. In the illustrated embodiment, the sequencer 60'is used to rotate pinion gears 70, 72, 74 secured onto the terminal ends of sleeves 32, 34, 36, respectively. It is also appreciated that one drive unit could be provided for indexing the carrier 20 while separately controlled devices could be used for effecting independent movement of the respective workpiece receiving arms. In accordance with the illustrated embodiment, which is schematic in nature, the sequencer 60 effects both the indexing movement and the controlled independent movement of the respective sleeves, and thus the respective arms. Various other arrangements could be devised for accomplishing this same purpose. Since this feature does not form an element of the present invention, the schematic illustration is used for simplicity.

Having thus defined my invention, I claim:

1. In a carrier for moving an elongated workpiece in a generally circular path from a loading station, to an induction heating station and then through a quenching station, said carrier having at least three members for supporting workpieces, the improvement comprising: means for allowing independent movement of each of said members with respect to the other of said members at least between said heating station and said quenching station.

2. The improvement as defined in claim 1 wherein said means for allowing independent movement allows such independent movement from said heating station to said quenching station.

3. The improvement as defined in claim 1 wherein said allowed independent movement is a maximum of approximately along said circular path.

4. An apparatus for inductively heating and quench hardening elongated workpieces having an axis, said apparatus comprising: first, second and third workpiece receiving members, each member including means for supporting a workpiece, means for rotating said workpiece about said axis, means for moving said workpiece in a path defining a circle about a common axis spaced from and parallel to said workpiece axis; means for moving said members in said path about said common axis from a loading station, to a heating station and then through a quenching station, an induction heating means for inductively heating at least a portion and means for moving said members, and workpieces carried thereby, from a loading station, to a heating station and then through a quenching station; an induction heating means for inductively heating at least a portion of said workpieces at said heating station; a quench tank means for maintaining a body of quenching liquid at said quenching station; and means for moving each of said members independently of said other members, at least between said heating station and said quenching station.

lO60l0 0292 

1. In a carrier for moving an elongated workpiece in a generally circular path from a loading station, to an induction heating station and then through a quenching station, said carrier having at least three members for supporting workpieces, the improvement comprising: means for allowing independent movement of each of said members with respect to the other of said members at least between said heating station and said quenching station.
 2. The improvement as defined in claim 1 wherein said means for allowing independent movement allows such independent movement from said heating station to said quenching station.
 3. The improvement as defined in claim 1 wherein said allowed independent movement is a maximum of approximately 120* along said circular path.
 4. An apparatus for inductively heating and quench hardening elongated workpieces having an axis, said apparatus comprising: first, second and third workpiece receiving members, each member including means for supporting a workpiece, means for rotating said workpiece about said axis, means for moving said workpiece in a path defining a circle about a common axis spaced from and parallel to said workpiece axis; means for moving said members in said path about said common axis from a loading station, to a heating station and then through a quenching station, an induction heating means for inductively heating at least a portion of said workpieces at said heating station; a quench tank means for maintaining a body of quenching liquid at said quenching station; and means for moving each of said members independently of said other members, at least between said heating station and said quenching station.
 5. An apparatus for inductively heating and quench hardening elongated workpieces having an axis, said apparatus comprising: a carrier for moving said workpieces in a path defining a circle about an axis; said carrier having at least three workpiece receiving members and means for moving said members, and workpieces carried thereby, from a loading station, to a heating station and then through a quenching station; an induction heating means for inductively heating at least a portion of said workpieces at said heating station; a quench tank means for maintaining a body of quenching liquid at said quenching station; and means for moving each of said members independently of said other members, at least between said heating station and said quenching station. 